There have been many changes in the radio industry over the last decade. Traditional analog terrestrial radio is no longer the exclusive provider of audio content to listeners. Digital audio communications, in a variety of forms, are becoming increasingly prevalent. Digital content (audio or otherwise) can be communicated in several different ways. Some common examples of communicating digital content include over the Internet, over the air through the use of satellites, or over the air through terrestrial means using appropriate transmitters.
One increasingly popular means for providing digital content is through satellite radio. Satellite radio has become widely used in the past decade. At this time, there are two main providers in the United States—XM and Sirius. These providers operate on a subscription (fee-based) basis and require listeners to use receivers with unique identification numbers to determine subscriber information. Because satellite radio in the United States operates on a subscription basis, the subscriber information is necessary for use in decoding the digital transmission received over the satellite broadcast. In addition to audio content that includes, but is not limited to, music, weather, sports, talk, and news, satellite providers are able to provide real-time traffic and weather information in both audio and non-audio form (e.g., text). More recently, Sirius and XM have begun to provide video content, as well, for providing television service to their subscribers.
The advent of HD Radio™ now provides for even more digital options. HD Radio™ is a predominately fee-free terrestrial alternative for providing digital content, which has been gaining ground in the past several years. Initially HD Radio™ stood for Hybrid Digital radio, based on the mode originally used for broadcasting. Today, however, HD Radio™ is a trademark of the iBiquity Digital Corporation. HD Radio™ uses an in-band on-channel (IBOC) technology that was selected by the Federal Communications Commission (FCC) in 2002 for terrestrial digital audio broadcasting in the United States. The specifications for the IBOC standard as used by HD Radio™ provides for both an “All Digital” and a “Hybrid Digital” operating modes. The hybrid mode of HD Radio™ operates in a similar manner as traditional analog stations, except that a digital data stream is transmitted in addition to the analog waveform signals. Currently, most stations offering HD Radio™ are using the hybrid mode. In the future, it is expected that an all digital signal will be more common. Multicasting, or providing more than one program over an existing spectrum, allows for more choices of content for users. However, similar to satellite radio, additional equipment must be purchased by users to receive HD Radio™. That is, an HD Radio™ receiver must be acquired that is capable of receiving multicast channels.
Regardless of the type of content delivery, a user may desire to listen to a song or program from the beginning, although the radio was not actively receiving the signal when the song or program initially began, as in the case of a user turning on the radio or switching channels in the middle of the song or program. In such circumstances where the user desires to hear the entire song or program, the user is simply “out-of-luck” with conventional radio equipment.